As interest in biometric recognition has increased in the security market, the market has expanded. The present invention pertains to the iris recognition sector of the biometric recognition field. Biometric recognition devices respond to various directions from which users approach them. However, since the directions from which users approach the devices are significantly different and varied depending on surrounding environments or the psychology of users, it is substantially difficult to make responses to all possible directions. Accordingly, there is a need for a user guidance method and device that are capable of improving the rate of recognition without deterring users.
Devices for capturing images of the irises are devices that allow light emitted from a light source to be reflected from the eyes of an iris-recognition target person and to enter cameras, extract images of the irises from images of the eyes, compare the images of the irises with iris data previously stored in a database, and then identify the irises.
In this case, in order to capture accurate images of the irises, a user should be located at a precise location for an iris recognition device. That is, the iris recognition device can capture accurate images of the irises only if it has guided a user to a precise location an appropriate distance away from the iris recognition device.
Iris recognition devices should capture images of the irises of users via cameras. In order to capture the irises of a user, a certain indicator is shown to a user and then the user is made to be positioned at an appropriate location while viewing the indicator. Although the types of indicators that can be presented are various, a single light source (an LED) is generally used as an indicator for the recognition of the irises. Furthermore, a half mirror is used to allow the user to determine whether he or she is accurately viewing the indicator.
FIG. 1 is a configuration diagram of a conventional device for capturing images of the irises. In a conventional device 100 for capturing images of the irises, when a user views a single indicator 101 through a half mirror 104, the user views a virtual image in which the indicator is located between the two eyes. This conventional device 100 for capturing images of the irises operates without any problem for users having a small difference in the field of vision between their two eyes.
However, in the case of a user having a large difference in the field of vision between his or her two eyes, the user should move his or her face to the left and right in order to locate the virtual image of the indicator between the two eyes.
FIGS. 2 and 3 illustrate this phenomenon.
FIG. 2 illustrates the case of a user having a good field of vision in his or her left eye, and FIG. 3 illustrates the case of a user having a good field of vision in his or her right eye.
Referring to FIG. 2, it can be seen that the field of vision of the left eye of the user is wider than that of the right eye of the user. In this case, when the user determines via the half mirror 204a of an iris recognition device 200a that an indicator LED 201a is located between his or her two eyes, the indicator LED 201a may be in the state of being biased to the left in reality. In this case, the left and right cameras 203a and 202a of the iris recognition device 200a cannot accurately capture the two eyes of the user.
Referring to FIG. 3, it can be seen that the field of vision of the right eye of the user is wider than that of the left eye of the user. In this case, when the user determines via the half mirror 204b of an iris recognition device 200b that an indicator LED 201b is located between his or her two eyes, the indicator LED 201b may be in the state of being biased to the right in reality. In this case, the left and right cameras 203b and 202b of the iris recognition device 200b cannot accurately capture the two eyes of the user.
The phenomena of FIGS. 2 and 3 occur in the case of users having large differences in the field of vision between their two eyes. So far, the reason why the conventional device for capturing images of the irises does not work for these users cannot be determined. In real life, when a human views an object at a specific location while covering only the left eye or only the right eye, the human feels that the object is viewed as moving from the left to the right or as moving in the reverse direction. This phenomenon is the reason why the right camera cannot accurately capture an image of the right eye and the left camera cannot accurately capture an image of the left eye, as illustrated in FIGS. 2 and 3.
In addition to iris recognition, there are various methods of recognizing a user, such as fingerprint recognition, recognition using a smartcard, etc. The market for access control using user recognition was opened and has been continuously expanding. Such access control technology have been used not only in the military and airports for the control of entry and exit into and from a security area but also in luxury apartments, prisons and fitness centers for the management of entry and exit and absenteeism and tardiness.